A turbomachine, such as a gas turbine, generally includes an inlet section, a compressor section, a combustion section that includes a plurality of combustors, a turbine section and an exhaust section. The inlet section cleans and conditions a working fluid (e.g., air) and supplies the working fluid to the compressor section. The compressor section progressively compresses the working fluid and supplies a high pressure compressed working fluid to the combustors where it is mixed with a fuel and burned in a combustion chamber to generate combustion gases having a high temperature and pressure. The combustion gases flow along a hot gas path into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a shaft connected to a generator to produce electricity.
Each combustor includes various hardware components. For example, a conventional gas turbine combustor may include one or more fuel nozzles, a combustion liner, a cooling flow sleeve, a transition duct, an impingement sleeve, a cap assembly and/or various mounting hardware such as brackets and radial compression or hula seals. The turbine generally includes various hardware components including stationary or stator vanes, rotatable turbine blades and rotor disks. Over time, various factors including thermal cycling, vibrations and/or pressure pulses within the gas turbine may result in hardware component degradation. As a result, regularly scheduled outages for inspection and repair must be executed, thus affecting machine availability.
Typically, gas turbines have control systems that monitor and control their operation. Conventionally, control systems execute various scheduling algorithms that adjust or control various effectors or gas turbine inputs such as fuel flow, inlet guide vane angles and other control inputs to provide safe and efficient operation of the gas turbine while governing various operational aspects of the gas turbine so as to meet power and efficiency objectives while simultaneously meeting predefined hardware component life requirements.
Gas turbine control systems typically receive as inputs various operating parameters and settings that, in conjunction with the scheduling algorithms, determine turbine control settings to achieve the desired operational mode or condition while still meeting hardware component life requirements. Measured or sensed operating parameters may include, but are not limited to, compressor inlet pressure and temperature, compressor exit pressure and temperature, turbine exhaust temperature, and generator power output. Desired operational modes or conditions may include, but are not limited to, full-speed full-load, base-load and turndown operation of the gas turbine. The operational modes are generally determined by one or more of desired generator power output, emissions limits and/or exhaust energy requirements such as for a combined cycle power plant which includes a heat recovery steam generator.
The scheduling algorithms (e.g., exhaust temperature vs. compressor pressure ratio, fuel splits vs. combustion reference temperature, inlet bleed heat vs. inlet guide vane (IGV) position, compressor operating limit line vs. corrected speed and IGV position, etc.) may be typically defined to protect the gas turbine against known operational boundaries or limits (e.g., emissions requirements, combustor dynamics, lean-blow-out, compressor surge, compressor icing, compressor clearances, aero-mechanical, etc.). The scheduling algorithms are typically based, at least in part, on off-line field tests, predefined design constraints and/or laboratory data.
Forcing strict operational compliance with a rigid schedule-based and/or model-based control system may result in economic performance loss at various operating modes such as at base load, full-speed full-load or turndown of the gas turbine, thus potentially affecting the overall economic benefits or potential profits of the gas turbine based power plant facility. Thus, there exists a need for a system and method for operating a gas turbine based power plant which allows an owner/operator the ability to evaluate the potential hardware component life effects of operating the gas turbine outside of the pre-defined scheduling algorithms based on a real-time or near-real time component hardware wear.